Acne is a disease of the pilosebaceous units of the skin and is characterized by the formation of comedones (whiteheads and blackheads); inflamatory papules; pustules and in more severe cases, inflammatory granulomas (cysts) and hypertrophic scars. Topical treatments for acne are mainly aimed at reducing the number of comedones and the intensity of inflammation. There are three known factors which are important in the pathogenesis of acne: (1) hyperactive sebaceous gland, (2) obstruction to the pilosebaceous apparatus by excessive keratinization of the follicula epithelial, and (3) initiation of the inflammatory process by a skin bacteria: Propionibacterium acnes.
Various treatments of acne are primarily focused on the three aforementioned factors. The suppression of sebaceous gland activity or sebum excretion rate can now be accomplished by the oral 13-cis retinoic acid therapy. The correction of the abnormal or excessive keratinization is accomplished by topical treatment with comedolytic agents such as transretinoic acid and salicylic acid which are effective in reducing the number of comedones. Reduction of the inflammation process can be achieved by the topical application of potent antimicrobial agent such as benzoyl peroxide which is extremely effective in reducing the number of the acne bacillus, Propionibacterium acnes.
However, the comedolytic agent salicylic acid does not possess any antibacterial activity against P. acnes nor does benzoyl peroxide possess any significant comedolytic activity. Recently, in U.S. Pat. No. 4,355,028, issued Oct. 19, 1982 to A. Kligman et al. it has been proposed to treat acne vulgaris with both salicylic acid and benzoyl peroxide at certain specified levels simultaneously or sequentially.
It is therefore highly desirable that a compound possessing both comedolytic and antibacterial activity against P. acnes be found to provide for a simplified yet improved treatment of acne and particularly acne vulgaris.